How quickly you move up in rank in the Marines depends on the quality of your service, how long you've been a Marine, how long you've served in your current position and your level of education. It is also be determined by what the needs of the Marine Corps are, as federal law mandates how many positions at each rank can be filled at any one time. Enlisted positions above lance corporal, as well as commissioned positions above second lieutenant, are limited. That's when getting a promotion gets competitive.

Early Enlistment

Enlisted service members usually graduate boot camp as privates at pay grade E-1. This is as basic as you can get. Promotion to private first class usually happens within the first six months of your tour, though it can happen sooner if your conduct is outstanding or if you have college credits under your belt. Getting promoted to lance corporal happens after you've been a private first class for eight months and is usually automatic, as long as you meet the basic criteria.

Moving Up as Enlisted

Promotions beyond E-3 are more performance-based than time-based. This is where composite scores are computed to evaluate your performance. To earn a promotion to E-4, or corporal, you must have been in the Marine Corps for at least a year and spent eight months of that time at E-3. Your scores for the quality of your service and as a rifleman are tallied at this point to determine your eligibility to move onward. To move on to sergeant, you must have two years in service and one year at E-4, and your scores must be excellent. Staff sergeants can earn their grades after four years of service and two years at their current grade, excellent scores and the completion of a professional military education course. Beyond this, promotion considerations must be presented to a selection board. Sergeant major, the highest enlisted rank possible, is reserved for one person at a time.

Commissioned Officers

The most basic qualification for a commissioned officer is being in possession of a four-year degree. Officers begin their careers with the Marine Corps as second lieutenants and are eligible to advance to first lieutenant after two years in service. To move beyond this, officers must both put in the time and have their service records evaluated by a selection board. As available slots are limited, only the most deserving officers will get promoted. Time-related eligibility is as follows: O-2 to captain, 0-3 is four years in service and two years in current grade; captain to major is nine to 11 years in service and three in grade; major to lieutenant colonel is 15 to 17 years in service and three in grade; and finally, lieutenant colonel to colonel is 21 to 23 years in service and three in grade. Pay grades above O-6 are generals and are extremely limited. Nominated officers are approved by the Senate before becoming generals.

Warrant Officers

Warrant officers are enlisted Marine service members who are given the responsibilities and respect of commissioned officers because they possess skills in highly specialized areas. Enlisted members at the rank of sergeant or above can apply as technical warrant officers if they've been in the service for at least eight but no more than 16 years. Gunnery sergeants can apply as non-technical warrant officers if they've been in for at least 16 but less than 23 years. Warrant officer promotions are competitive. Warrant officers at pay grade W-1 are eligible for promotion after 18 months in grade. Subsequent promotions are the same but there must be vacancies in that grade for officers to earn promotion.